A promising scalable bar coating approach using a single crystal-derived precursor ink for high-performance large-area perovskite solar cells

Perovskite solar cells (PSCs), with demonstrated high efficiencies in a lab scale, are regarded as potential energy-harvesting materials if the challenges like large-area manufacturing and long-term stability are achieved. In an effort to fabricate PSCs on large-area substrates, the study herein reports the use of an economic and scalable bar coating method for the fabrication of PSCs. Bar coating is used initially to coat electron transport layers on large-area (50 mm × 50 mm) FTO glass substrates. A methyl ammonium lead iodide (MAPbI3) perovskite absorber has been bar coated on the electron transport layers coated FTO glass substrates using a single-crystal-derived perovskite precursor. The single crystal-derived precursor has resulted in large-area uniform perovskite absorbers and, thus, characterized appositely to establish the uniform coverage of desired quality MAPbI3. The spatial distribution of photoluminescence and absorption spectra of the perovskite absorber, collected systematically, confirms the device quality MAPbI3, with identical characteristics ascertaining the homogeneity of perovskite coating. Solar cells fabricated using bar-coated large-area perovskite absorbers have exhibited a champion power conversion efficiency of 15.6%, with the average power conversion efficiency being 14.5%, unveiling an excellent performance homogeneity. Further, the champion devices of bar-coated PSCs are compared with control devices fabricated by spin coating of a powder-derived precursor. Bar-coated PSCs have not only exhibited significantly higher performance but also showed comparable reproducibility and much lower hysteresis values than the control PSCs, demonstrating the efficacy of the bar coating method towards fabricating large-area PSCs.